Process for separation of the constituents of gaseous mixtures.



1 G. CLAUDE. PROCESS FOR SEPARATION OF THE GONSTITUENTS OF GASEOUSMIXTURES.

APPLICATION FILED I'EB.10, 1911.

Patented July 22, 1913 2 SHEETS-SHEET 1.

iii :3]

Inventor.

Witnesses.

G. CLAUDE.

PBOGBSS FOR SEPARATION OF THE GONSTITUBNTS 0F GASEOUS MIXTURES.

APPLICATION FILED FEB. 10, 1911.

Patented July 22, 1913.

2 SHEETSSHEET 2.

. Inventor. 6

Win? ITED STATES PATENT OFFICE.

GEORGES CLAUDE, OF PARIS, FRANCE, ASSIGNOR TO SOCIETE LAIR LIQUIDE(SOCIETE ANONYME POUR LETUIDE ET LEKPLOITATION DES PROCEDES GEORGESCLAUDE),

01E PARIS, FRANCE.

rocaa'ia.

Specification of Letters Patent.

Application filed February 10, 1911.

Patented July 22, 1913.

Serial No. 507,?75.

To all whom it may concern:

Be it known that I, Geonons CLAUDE, a citizen of the Republic of France,residing at 48 Rue St. Lazare, Paris, in the Republic of France, haveinvented certain new and useful Improvements Relating to the Separationof the Constituents of Gaseous Mixtures, of which the following is aspecification.

This invention relates to the separation of the constituents of gaseousmixtures, particularly of atmospheric air.

In my co-pending application, Serial No. 550,005, filed March 17, 1910,a process has been described in which the air from a single airsupplypasses in succession through two tubular systems at the footof arectification column. Two separate liquids, one rich in oxygen and theother rich in nitrogen, were thus produced and it was also pointed outthat although the liquid rich in nitrogen contained'a sufiiciently highpercentage of nitrogen to be satisfactory for most pur-' poses, a liquidof still greater purity could be obtained by subjecting the gaseousresidue escaping from the liquid rich in nitrogen to the cooling actionof a liquid that was colder than either of the liquids used to producethe aforesaid two liquids rich in oxygen and in nitrogen respectively.For this purpose the cold liquid escaping directly from the bottom plateof the usual rectification column was used and liquid nitrogen of almostchemical purity was thereby obtained. The chief object of the presentinvention is to simplify this process and to increase the quantity ofalmost chemically pure nitrogen obtainable.

According to the present invention the gaseous mixture passes insuccession through two tubular systems of which the first system iscooled by the liquid collected at the foot of the usual rectificationcolumn, but the liquefaction in the second tubular system is effected byusing a liquid that has collected in the rectification column in aregion situated some distance above the lowermost plate of the columnand that is in course of rectification and is therefore colder thanthatcollecting actually at the foot of the column. For this purpose thesecond tubular system is conveniently situated within the column at anintermediate point in its height, and may if desired be so arranged thatliquefaction takes place in it on the principle of liquefaction withreturn flow of the liquid, as is the case in the'first of the tubularsystems. The two separate liquids before being introduced at appropriatepoints near the top of the column may be passed through cooling coilssituated in the rectification column in a region above that where therespective liquefactions took place.

Further steps in the process relate to the treatment of the gaseousresidues escaping from different parts of the column as hereinafterdescribed.

In order that the invention may be clearly understood and readilycarried into effect, the same will now be described more fully withreference to the accompanying drawings in which Figure 1 illustratesdiagrammatically one constructional form of apparatus adapted to operatein accordance with the invention. F ig. 2 is a view of a portion of therectification column of the apparatus, in which a modified constructionis adopted. Fig. 3 is a further view of a portion of the rectificationcolumn, showing also means for separating out argon, as hereinafter setforth. Fig. 4 is a modifiedform of the base of the rectification column.

Referring first to Fig. 1, it will be seen that the air, after beingbrought to the proper pressure and temperature, enters at A at the baseof a vertical nest of tubes F, surrounded by liquid oxygen or liquidrich in oxygen which liquid has collected in a vaporizing vessel C atthe base of the rectification column and undergoes evaporation therein;as pointed out in the prior specification, it is preferable that theupper part only of this nest of tubes F should be immersed in the liquidto be vaporized. The gaseous residue of the liquefaction with returnflow of the liquid in this nest of tubes F ascends throu h a tube T andenters a second nest of in es S immersed in some of ducted through apipe T to the top ofthe rectification column, where it is discharged,

and in order to prevent its partial evaporation at the moment ofdischarge, it is advisthe-rectification column. It may likewise beadvantageous to cool under pressure, by means of a similar circulationin coil 5 the liquid rich in oxygen obtained in the first stage of theliquefaction of the air. The regulating cocks or valves V and V throughwhich these two liquids, namely the PIaCtlr cally pure liquid nitrogenand the liquid rich in oxygen, flow on their way into the rectifyingcolumn, are arranged beyond their respective cooling coils. If it isfound that the total area of the condensation surface of the tubes S isat any time excessive, this area may be reduced by regulating the valveV in such a manner as to cause some liquid to collect in the lower partof the tubes S, thus reducing their effective area for condensation.

The practical execution of this process is subjected to the followingobservation: When it is desired to obtain nitrogen in a practically purestate, the rectification work of the column and the steadiness of theoperation are greatly facilitated if, instead of withdrawing the oxygenas gas in a ractically pure state, it is withdrawn wlth a certainquantity of nitrogen, that is to say in the state of eighty per cent.oxygen for example. However, the advantage thus. secured would entail adefect in that the liquid, which, under these conditions, falls from thelast plate of the rectification column into the vaporizing vessel C,instead of being almost pure oxygen, would necessarily be only at apercentage corresponding to that "of the extracted gas, that is to say,eighty per cent. oxygen for example. In practice, on account of theunavoidable disturbances incidental to working (such as variations inthe supply of compressed air, etc.,) the percentage of this. liquidundergoes appreciable fluctuations, for example from seventy to ninetyper cent, and its boiling pointnaturally undergoes alsd correspondingvariati ons. As this temperature (the boiling point)- is just the one atwhich the liquefaction of the incoming air requires to be carried out inthe tubes of the vaporizing vessel C, this actual liquefaction wouldthus be constantly disturbed; this would result in a continuousirregularity in the working of the apparatus and a diflicult managementwhich might counterbalance the advantage referred to above as beingderived by withdrawing gas containing eighty per cent. of oxygenr Inorder to obviate this defect, an advantageous procedure is as follows:Insteadof withdrawing the gaseous oxygen at the level of the vaporizingvessel C, impure oxygen is withdrawn at a higher level, for example atthe level of the second or third plate from the base of therectification column, as in-- dicated at 0. Under such conditions theliquid of the column will reach the level of the oxygen outlet with acomposition which is necessarily equal to that of the oxygenwithdrawn-say eighty per cent. oxygen by way of examplebut this liquidis rapidly converted into liquid oxygen as it completes its descent ofthe column owing to its meeting with the whole of the gaseous oxygenwhich ascends in this part of the column; hence, in this manner, thevaporizing vessel is supplied with liquid oxygen of the desired purity,the temperature of which is almost invariable.

In the foregoing description it has been assumed that the gases tobeliquefied are conducted in an upward direction by the first nest oftubes and in adownward direction by the second nest of tubes. If,however, it is desired to obtain gases of extremely low boiling point,such as neon, or helium, it is' preferable for the second nest of tubesto conduct the gases in an upward direction so that the liquefaction inthese tubes can take place with return flow of theliquid. Such anarrangement is illustrated in Fig. 2, in which the second part of thetubular system consists of an ascending nest of tubes S into which thegas to be liquefied is introduced at the bottom and after becomingliquid flows backward. The gaseous residue,- rich in neon and helium,which reaches the summit of these tubes, can then be collected at theexterior, or sent under pressure through a tube t toward a device S inwhich the said residue undergoes a last enrichment. I

It may be desirable to effect a withdrawal of a high proportion of theargon contained in the air treated, which argon would otherwise minglepartly with the oxygen and partly with the nitrogen. Now the volatilityof argon is intermediate between that of oxygen and that of nitrogen.The argon is forced toward the base of the rectification column by thestream of liquid nitrogen'discharged into the column at the summit ofthe latter and tends to accumulate, in part, with the oxygen in thevaporizing vessel and to such an extent that the principal impurity ofthe oxygen near the base of the column is constituted by argon and notby nitrogen. Nevertheless this argon, being more volatile than theoxygen, does not doncentrate without difiiculty in the actual liquidoxygen, but accumulatcs rather on the lower plates of the column, to anextent which may reach ten per cent. In short, during the first fewhours of the operation of the apparatus, an actual accumulation of argontakes place on these last plates, and it is when this accumulationsuffices to produce a sufliciently high vapor pressure of the argon,that this gas is able'to escape, partly to the oxygen,

roeaare and partly to the nitrogen, and to such an extent as tocounterbalance the fresh quantities of argon which occur in the air tobe treated and which are therefore being constantly supplied inproportion to the constant supply of air. The method adopted forremedying this condition of affairs consists broadl in providing aspecial door of escape or the argon; one method of doing so isillustrated diagrammatically in. Fig. 3 and consists in conducting, by atube T some of the gases rich in argon, existing above one of the lowerplates of the rectification column, through a coil B immersed in therelatively .cold liquid which is situated at about the upper third ofthis column. The oxygen of these gases liquefies with return flow of theliquid in the coil'B and flows back automatically toward the plate fromwhich the gas comes, while the gaseous residue, which is very rich inargon, is Withdrawn in the desired proportion, by suitably opening thecock R, and is collected outside after having yielded up its cold ifnecessary. The coil should not be arranged in the exceedingly cold zonesof the column because the argon might solidify there, as its point ofcongelation is-l90 C. approximately. It is obvious that this method ofpurifying the gases of the rectification column is applicable, whatevermay be thle method adopted for liquefying the compressed air supplied atthe foot of the column.

In the above description it has been assumed that liquid rich in oxygencollects at the foot of therectification column in a vaporizing vessel,a11d-'--that this vessel surrounds the upper part' of the first nest oftube If it were desired to obtain some practically pure oxygen, a shortadditional rectification column as illustrated by the plates E in Fig.at might be arranged beneath the main vaporizing vessel G and around theaforesaid nest of tubes F, and the liquid rich in oxygen might be madeto overflow the main vaporizing vessel and descend the short additionalrectification.

column beneath it. The practically pure oxygen thereby produced andcollected in the compartment Gr surrounding the lower end of the tubes Fat the foot of this short additional rectification 'column is allowed toundergo a final vaporization; part of the resulting vapor is withdrawn.as practically pure oxygen, through the opening U, and used for anydesired purpose, and the remainder, containing a certain proportion ofnitrogen, can be drawn out of the column through the opening \V, afterhaving assisted in the above mentioned additional rectification.

What- I claim is 1. A process for the separation of a mixture'of gases,such as air, into its constituents by way of liquefaction followed byrectification of the liquid produced, consisting in passing thecompressed and cooled gases through a laterally confined space cooled byliquid collected at the footof the usual rectification column, and thenpassing the remaining unliquefied gases in continuation through a secondlaterally confined space cooled by liquid collected in the column in aregion situated some distance above the foot of the column.

2. A process for the separation of a mixture of gases, such as air, intoits constituents by way of liquefaction followed by rectification of theliquid produced, consisting inpassing the compressed and cooled gasesthrough an upwardly conducting laterally confined space cooled by liquidcollected at the foot of the rectification colman, and then passing theremaining unliqnefied gases in continuation through a second upwardlyconducting laterally confined space cooled by liquid collected in thecolumn in a region situated some distance above the foot of the column.

3. A process for the separation of a mixture of gases, such as air, intoits constituents by way of liquefaction followed by rectification of theliquid produced, con sisting in temporarily arresting and collecting theliquid at an intermediate point in its descent of the usualrectification column, passing the compressed and cooled gases through anupwardly conducting laterally confined space cooled by liquid collectedat the foot of the column, and then passing the remaining unliquefiedgases in continuation through a second laterally confined space cooledby the aforesaid temporarily arrested and collected liquid.

4. A process for the separation of a mixture of gases, such as air, intoits constituents by way of liquefaction followed by rectification of theliquid produced, consisting in passing the compressed and coo'ed gasesthrough an upwardly conducting lat erally confined space the upper partof which is kept at a lower temperature than the lower part bysurrounding the upper part. with liquid collected at the foot of theusual rectification column, and then passing the remaining unliquefiedgases in continuation through a second laterally con-- fined spacecooled by liquid collected in the column in a region situated somedistance above the foot of the column.

5. A process for the separation of a mixture of gases, such as air, intoits constituents by way of liquefaction followed by rectification of theliquid produced, consist-- ing in passing the compressed and cooledgases through an upwardly conducting lateially confined space the upperpart of which is kept at a lower temperature than the lower part bysurrounding the upper part with liquid collected at the foot of theusual rectification column, and then passlng the remaining unliquefiedgases in continuation through a second upwardly' rectification of theliquid produced, consisting in passing the compressed and cooled gasesthrough an upwardly conductin laterally confined space cooled by liquicollected at the foot of the rectification column, then passing theremaining unliquefied gases in continuation through a second laterallyconfined space cooled by liquid collected in the column in a regionsituated some distance above the foot of the column, passing the twoliquids produced in the aforesaid confined spaces into the rectificationcolumn at its upper part and conducting one of the two liquids through alaterally confined space on its way to the rectification column, saidspace being situated in the column at a point above that where theproduction of the liquid took place.

7. A process for the separation of a mixture of gases, such as air, intoits constituents by way of liquefaction followed by rectification of theliquid produced, consisting in passing the compressed and cooledgasesthrough'an upwardly conducting laterally confined space cooled byliquid collected at the foot of the rectification column, then passingthe remaining unliquefied gases in contiuation through a secondlaterally confined space cooled by liquid collected in the column in aregion situated some distance above the foot of the column, passing thetwo liquids produced in the aforesaid confined spaces into therectification column at its upper part, and conducting each of the twoliquids through a laterally confined space on its way to therectification column, said space being situated in the column at a pointabove that where the production of theliquid took place.

, 8. A process for the separation of a mixture of gases, such as air,into its constituents by way of liquefaction followed by rectificationof the liquid produced, consisting in passing the compressed and cooledgases through an upwardly conducting. laterally confined space cooled byliquid collected at the foot of the rectification column, then" passingthe remaining unliquefied gases in continuation through a secondupwardly conducting laterally confined space cooled by liquid collectedin-the column in a region situated some distance above the foot of thecolumn, and passing the remaining unliquefied gases through a thirdupwardly conducting laterally confined space cooled to a lowertemperature than that of the first and second confined spaces, forobtainlIlg rare gases.

\ 9. A process for the separation of a mixture of gases, such asa-ir,-into its constituents by way of liquefaction followed byrectification of the liquid produced, consisting in passing thecompressed and cooled gases through an upwardly conducting lat-, erallyconfined space cooled by liquid collected at the foot of therectification column, then passing the remaining unliquefied gases incontinuation through a second laterally confined space cooled by liquidcollected in the column in a region situated some distance above thefoot of the column, passing some of the gases liberated near butslightly above the foot of the column through an upwardly' conductinglaterally confined space cooled by the liquid descending the column atits upper part, returning to the column the liquid producedin thelast'mentioned confined space, and conducting the unliquefied gaseousresidue, rich in argon, out of the said space and away from the column.

10. A process for the separation of a mixture of gases, such as air,into its constituents by way of liquefaction followed by rectificationof the liquid produced, consisting in passing the compressed and cooledgases through an upwardly conducting laterally confined space cooled byliquid collected at the foot of the rectification column, then passingthe remaining unliquefied gases in continuation through a secondlaterally confined space cooled by liquid collected in the column in -aregion situated some distance above the foot of the column, passing thetwo liquids produced in the aforesaid confined spaces into therectification column at its upper part, andvsubjecting the liquidcollected at the foot of the rectification column to an additionalrectification in the neighborhood of the first of the above men-- tionedlaterally confined spaces through which the compressed and cooled gasesare conducted. a

11. A process, for the separation of a mixture of gases, such as air,into its constituents by way of liquefaction followed by rectificationof the liquid produced, consisting in passing the compressed and cooledgases through an upwardly conducting laterally confined space cooled byliquid collected at the foot of the rectification column, passing thetwo liquids produced in the aforesaid confined spaces into therectification column at its upper part, subjecting the liquid collectedat the foot of the rectification column to an additional rectificationin the neighborhood of the, first of the above which the compressed andcooled gases are conducted, collecting the liquid resulting from thisadditional rectification, withdraw- -ing part of the vapor arising fromit direct away from the rectification column, and

conducting the remaining vapor upward in contact with the descendingliquid undergoing the said additional rectification.

12. A process for the separation of a IIliX- I ture of gases, such asair, into its constitlected at the foot of the rectification column.

then passing the remaining unliquefied gases in continuation through asecond laterally confined space cooled by liquid collected inthe columnin a region situated some dis tance above the foot of the column, andwithdrawing, at a point in the column a short distance above the foot ofthe same, some of the vapor of the liquid undergoingrectification as itreaches that point.

In testimony whereof I atliX my signature is presence of two witnesses.

' GEORGES CLAUDE. \Vitnesses PIERRE HOURLIER, DEAN B. MASON.

